The Ruger 10/22® rifle, first introduced in 1964, is a very popular semi-automatic rim-fire firearm in .22LR caliber manufactured by Sturm, Ruger & Co. of Southport, Conn. Others have made variations to the basic rifle, including modified barrels, additional safety mechanisms, modified trigger mechanisms, caliber changes, and modifications to the stock. The bolt and internal dimensions of the 10/22® receiver have remained unchanged and are widely recognized as standardized. The dimensional specifications for these parts have been published and are available to the public (or for purchase) simply by searching “10/22 blueprint” images on an on-line search engine. As a result, interchangeable aftermarket parts are widely available.
As produced by Ruger, both the 10/22® rifle and Charger™ pistol use a functionally identical receiver and include a charging handle which extends laterally from the right side of the receiver. Accordingly, it is awkward at best to manually cycle the action with the user's left hand. A right handed shooter is not naturally inclined to reach across the rifle and charge the bolt on the right side of the rifle with his left hand. Instead, the user typically must put the rifle in his left hand and operate the charging handle with his right hand, which takes his shooting grip off the rifle each time.
The standard lateral charging handle mates to, and reciprocates with, the bolt (or breech block). Because the handle represents a mass that reciprocates each time the action cycles, changing its size (and, hence, its mass) as others have done for ease of manual operation may affect the proper cycling of the action. In other cases, the mass may be intentionally altered in order to achieve proper cycling when different ammunition loads or ammunition of a different caliber is used. For example, bolt handle modifications are discussed in U.S. Pat. No. 7,302,881, entitled Conversion Kit and Method for a Ruger 10/22 Semi-automatic .22 Caliber Rim Fire Rifle to Shoot .17 MACH 2 Cartridges, issued Dec. 4, 2007, and in U.S. Patent Application Publication No. 2008/0083319, entitled Charging Handle, published Apr. 10, 2008.